High-power multi-stage klystron with adjustable periodic magnetic focussing



30, 8 w. SCHMIDT 3,366,904

HIGH-POWER MULTISTAGE KLYSTRON WITH ADJUSTABLE PERIODIC MAGNETIC FOCUSSING Filed Dec. 14, 1965 3 Sheets-Sheet 1 INVENTOR.

WOLFGANG SCHMIDT Jan. 30, 1968 SCHMIDT 3,366,904

HIGH-POWER MULTI-STAGE KLYSTRON WITH ADJUSTABLE PERIODIC MAGNETIC FOCUSSING Filed Dec. 14, 1965 5 Sheets-Sheet 2 AGENT W. SCHMIDT Jan. 30, 1968 HIGH-POWER MULTI-STAGE KLYSTRON WITH ADJUSTABLE PERIODIC MAGNETIC FOCUSSING Filed Dec. 14, 1965 3 Sheets-Sheet 3 FIGB INVENTOR' WOLFGA NG SCHMIDT AGENT States Patet 3,366,994 Patented Jan. 30, 1968 3,366,904 HIGH-POWER MULTI-STAGE KLYSTRON WETH ADJUSTABLE PERIODIC MAG- NETIC FOCUSSING Wolfgang Schmidt, Hamhurg-Uthmarschen, Germany, as-

signor to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Filed Dec. 14, 1965, Ser. No. 513,724 3 Claims. (Cl. 335-211) ABSTRACT OF THE DISCLOSURE A klystron employing periodic magnetic focussing of the electron beam in which the magnet systems for focussing the electron beam include adjustable magnetic shunts for most efiicient operation at a given potential of the beam.

This invention relates to high power multistage klystrons comprising a plurality of unidirectional permanent magnetic systems which together produce a spatial pcriodic magnetic field for focussing the electon beam and Which include adjustable magnetic shunts.

In such magnetic systems magnetic fields are produced along the axis of the electron beam within the permanent magnetic systems and oppositely directed fields are produced between the permanent magnetic systems. The strength of the magnetic fields required for the most eflicient operation at a given potential of the beam is adjusted by means of magnetic shunts. Since the shunts must be accurately adjustable, they can govern only a small range of the operating voltages of such a klystron.

An object of the invention is to provide a construction in which matching to a large range of voltages may be obtained in a simple manner.

According to the invention, in a high power multistage klystron having a plurality of unidirectional permanent magnetic systems which together produce a spatial periodical magnetic field for focussing the electron beam and which include adjustable magnetic shunts, each shunt comprises a fixed portion and a continuously adjustable portion. The voltage range in which the tube can operate may be determined by the fixed portion and the correct matching is obtained with the adjustable portion of the shunt. The fixed portion of the shunt is realized as a plurality of parts one or more of which may be omitted, or the parts of the shunts are exchangeable for parts of other magnetic reluctance or again the fixed parts are connected to the magnetic system leaving a certain air-gap. It is thus achieved, that the fine adjustment of the magnetic field over the whole range of voltages of the klystron is retained.

The invention will now be described with reference to the accompanying drawing in which:

FIG. 1 shows a klystron comprising magnetic system according to the invention;

FIG. 2 is a view in the axial direction and,

FIG. 3 a side view thereof.

In FIG. 1, an electron beam 1 emerging from a prefocussing system and extending along an axis 3 is indicated by an arrow. The focussing system comprises a plurality of identical axial magnetic systems 4 and a single system 5 comprising magnets magnetized in the radial direction. The magnetic systems 4 and 5 are separated by resonant cavities 6 of the klystron and a collector 7 lies externally of the system 5. The magnetic systems (see FIGS. 2 and 3) each comprise four axially directed, magnetically parallel columns 8 of ceramic permanent mag netic material. The columns 8 are connected through softmagnetic yokes 9 to pole pieces 10. The pole pieces 10 have circular apertures 11 which surround travelling spaces 12 of the klystron. The pole pieces 10 produce between said travelling spaces periodic magnetic fields directed along the axis 3 of the klystron. Soft-magnetic plates 13 are arranged at a short distance from the yokes 9 for the fine adjustment of the magnetic fields, said plates being adjustable in directions indicated by arrows 16 by means of screw spindles 14 provided with knobs 15. The screw spindles 14 are supported in non-ferromagnetic caps 17. The control range of the plates 13, which is only small, is adjusted by means of strips 18 of soft-magnetic material which adjoin faces 19 of the yokes 9 and are secured thereto by threaded bolts 20. The strips 18 and the faces 19 are separated by plates of non-ferromagnetic material, for example, aluminum, or these plates may be omitted.

A wide choice in the region of adjustment of the magnetic field in which the plates 13 bring about the fine adjustment is possible by suitable choice of the cross-section of the strips 18, the number thereof and the thickness of intermediate layers 21.

What is claimed is:

1. A high power multistage klystron comprising a plurality of unidirectional permanent magnetic systems which together proudce a spatial periodic magnetic field for focussing an electron beam and which include adjustable magnetic shunts, each of said shunts comprising a fixed portion and a continuously adjustable portion.

2. A multistage klystron as claimed in claim 1, characterized in that the fixed portion of a shunt comprises a plurality of changeable parts.

3. A multistage klystron as claimed in claim 1 characterized in that the magnetic systems and the fixed shunts are separated by non-ferromagnetic material.

References Cited FOREIGN PATENTS 953,268 3/1964 Great Britain.

BERNARD A. GILHEANY, Primary Examiner. G. HARRIS, Assistant Examiner. 

